Restructure: Move 52 files into 7 domain packages

korrektur/ zeugnis/ admin/ compliance/ worksheet/ training/ metrics/
52 shims, relative imports, RAG untouched.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

klausur-service/backend/admin/api.py

@@ -0,0 +1,33 @@
+"""
+Admin API for NiBiS Data Management (barrel re-export)
+
+This module was split into:
+  - admin_nibis.py      (NiBiS ingestion, search, stats)
+  - admin_rag.py        (RAG upload, metrics, storage)
+  - admin_templates.py  (Legal templates ingestion, search)
+
+The `router` object is assembled here by including all sub-routers.
+Importers that did `from admin_api import router` continue to work.
+"""
+
+from fastapi import APIRouter
+
+from .nibis import router as _nibis_router
+from .rag import router as _rag_router
+from .templates import router as _templates_router
+
+# Re-export internal state for test importers
+from .nibis import (  # noqa: F401
+    _ingestion_status,
+    NiBiSSearchRequest,
+    search_nibis,
+)
+from .rag import _upload_history  # noqa: F401
+from .templates import _templates_ingestion_status  # noqa: F401
+
+# Assemble the combined router.
+# All sub-routers use prefix="/api/v1/admin", so include without extra prefix.
+router = APIRouter()
+router.include_router(_nibis_router)
+router.include_router(_rag_router)
+router.include_router(_templates_router)